Outputs

Fig. 2 Data Link (Diagnostic) Connector:

DATA LINK CIRCUITS
The Powertrain Control Module (PCM) communicates with the DRB Scan Tool through the data link receive and transmit circuits. Technicians can connect the DRB Scan Tool to the data link connector. The data link connector contains 16 terminals. Terminal 6 is the Data Link Engine Receive circuit. Terminal 7 is the Data Link Engine Transmit (K-Line) circuit.

DATA LINK CONNECTOR
The data link connector (diagnostic connector) links the DRB scan tool with the Powertrain Control Module (PCM). Refer to On-Board Diagnostics in Emission Control Systems. The data link connector is located inside the vehicle, under the instrument panel, at the driver's kick panel Fig. 2.

Fig. 25 Power Distribution Center (PDC):

AIR CONDITIONING CLUTCH RELAY - PCM OUTPUT
The PCM controls the air conditioning clutch relay ground circuit. Buss bars in the Power Distribution Center (PDC) supply voltage to the solenoid side and power side of the relay.

When the PCM senses low idle speeds or wide open throttle through the throttle position sensor, it removes the ground for the A/C compressor clutch relay. When the relay de-energizes, the contacts open preventing air conditioning clutch engagement.

The air conditioning clutch relay is located in the PDC Fig. 25. The inside top of the PDC cover has a label showing relay and fuse location.

AUTOMATIC SHUTDOWN RELAY - PCM OUTPUT
The Automatic Shutdown (ASD) relay supplies battery voltage to the fuel injectors, electronic ignition coil and the heating elements in the oxygen sensors.

A buss bar in the Power Distribution Center (PDC) supplies voltage to the solenoid side and contact side of the relay. The ASD relay power circuit is supplied by a 20 amp fuse in the PDC. Refer to Wiring Diagrams for circuit information.

The PCM controls the relay by switching the ground path for the solenoid side of the relay on and off. The PCM turns the ground path off when the ignition switch is in the Off position unless the 02 Heater Monitor test is being run (2.0L only). Refer to On-Board Diagnostics. When the ignition switch is in the On or Crank position, the PCM monitors the crankshaft position sensor and camshaft position sensor signals to determine engine speed and ignition timing (coil dwell). If the PCM does not receive the crankshaft position sensor and camshaft position sensor signals when the ignition switch is in the Run position, it will de-energize the ASD relay.

The ASD relay is located in the PDC Fig. 25. The inside top of the PDC cover has a label showing relay and fuse location.

CHARGING SYSTEM INDICATOR LAMP - PCM OUTPUT
The PCM sends a message over the CCD Bus to the Body Control Module (BCM). The BCM turns the instrument panel Charging System Lamp on. Refer to Charging System for more information.

Fig. 26 Duty Cycle EVAP Purge Solenoid:

DUTY CYCLE EVAP PURGE SOLENOID - PCM OUTPUT
The duty cycle EVAP purge solenoid regulates the rate of vapor flow from the EVAP canister to the throttle body The PCM operates the solenoid.

During the cold start warm-up period and the hot start time delay the PCM does not energize the solenoid. When de-energized, no vapors are purged.

The engine enters closed loop operation after it reaches a specified temperature and the programmed time delay ends. During closed loop operation, the PCM energizes and de-energizes the solenoid 5 to 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time the solenoid is energized.

The solenoid attaches to a bracket on the driver's side strut tower Fig. 26. To operate correctly, the solenoid must be installed with the electrical connector on top.

Fig. 27 Electronic EGR Transducer:

ELECTRIC EGR TRANSDUCER - PCM OUTPUT
The Electric EGR Transducer contains an electrically operated solenoid and a back-pressure controlled vacuum transducer Fig. 27. The PCM operates the solenoid based on inputs from the multi-port fuel injection system. The solenoid/transducer and EGR valve are serviced as an assembly.

When the PCM energizes the solenoid, vacuum does not reach the transducer. Vacuum flows to the transducer when the PCM de-energizes the solenoid.

When exhaust system back-pressure becomes high enough, it fully closes a bleed valve in the vacuum transducer. When the PCM de-energizes the solenoid and back-pressure closes the transducer bleed valve, vacuum flows through the transducer to operate the EGR valve.

De-energizing the solenoid, but not fully closing the transducer bleed hole (because of low back-pressure), varies the strength of the vacuum signal applied to the EGR valve. Varying the strength of the vacuum signal changes the amount of EGR supplied to the engine. This provides the correct amount of exhaust gas recirculation for different operating conditions.

Fig. 29 EGR Control Valve:

The solenoid/transducer and EGR valve mount to the rear of the cylinder head Fig. 29.

Fig. 30 Fuel Injector:

FUEL INJECTORS - PCM OUTPUT
All these engines use electrically operated top feed fuel injectors Fig. 30. The Automatic Shutdown (ASD) relay supplies battery voltage to the fuel injectors. The PCM controls the ground path for each injector in sequence. By switching the ground paths on and off, the PCM fine-tunes injector pulse width. Injector pulse width refers to the amount of time an injector operates.

The PCM determines injector synchronization from the camshaft position sensor and crankshaft position sensor inputs. The PCM grounds the ASD and fuel pump relays after receiving the camshaft position sensor and crankshaft position sensor inputs.

The PCM energizes the injectors in a sequential order during all engine operating conditions except start-up. For the first injector pulse width during start-up, all injectors are energized at the same time. Once the PCM determines crankshaft position, it begins energizing the injectors in sequence.

FUEL PUMP RELAY - PCM OUTPUT
The fuel pump relay supplies battery voltage to the fuel pump. Power for the solenoid is supplied through a 10A fuse in the Junction Block. The contacts are supplied power through a 20A fuse in the PDC. Refer to Wiring Diagrams for circuit information.

The PCM controls the fuel pump relay by switching the ground path for the solenoid side of the relay on and off. The PCM turns the ground path off when the ignition switch is in the Off position. When the ignition switch is in the On position, the PCM energizes the fuel pump. If the crankshaft position sensor does not detect engine rotation, the PCM de-energizes the relay after approximately one second.

The fuel pump relay is located in the PDC Fig. 25. The inside top of the PDC cover has a label showing relay and fuse location.

Fig. 32 Idle Air Control Motor:

IDLE AIR CONTROL MOTOR - PCM OUTPUT
The Idle Air Control (IAC) motor is mounted on the throttle body. The PCM operates the idle air control motor Fig. 32. The PCM adjusts engine idle speed through the idle air control motor to compensate for engine load, coolant temperature or barometric pressure changes.

The throttle body has an air bypass passage that provides air for the engine during closed throttle idle. The idle air control motor pintle protrudes into the air bypass passage and regulates air flow through it.

The PCM adjusts engine idle speed by moving the IAC motor pintle in and out of the bypass passage. The adjustments are based on inputs the PCM receives. The inputs are from the throttle position sensor, crankshaft position sensor, coolant temperature sensor, MAP sensor, vehicle speed sensor and various switch operations (brake, park/neutral, air conditioning and power steering).

IGNITION COIL - PCM OUTPUT
Refer to Ignition Systems for information.

MALFUNCTION INDICATOR LAMP (MIL) - PCM OUTPUT
If a problem is detected, the PCM sends a message over the CCD Bus to the Body Control Module (BCM). The BCM interprets this message and sends a signal to the instrument cluster to illuminate the malfunction indicator (Check Engine) lamp. The lamp comes on each time the ignition key is turned ON and stays on for a 3 second bulb test.

The MIL lamp stays on continuously when the PCM has entered a Limp-In mode or identified a failed emission component. During Limp-in Mode, the PCM attempts to keep the system operational. The malfunction indicator lamp signals the need for immediate service. In limp-in mode, the PCM compensates for the failure of certain components that send incorrect signals. The PCM substitutes inputs from other sensors for the incorrect signals.

If the PCM detects active engine misfire sever enough to cause catalyst damage, it flashes the malfunction indicator (Check Engine) lamp. At the same time the PCM also sets a Diagnostic Trouble Code (DTC).

Signals that can trigger the Malfunction Indicator Lamp (MIL).
- Camshaft Position Sensor
- Intermittent Cam or Crank Sensor
- Deteriorated Catalytic Convertor
- Deteriorated Fuel System
- Deteriorated EGR System
- Deteriorated EVAP System
- Deteriorated Heated Oxygen Sensors
- Engine Coolant Temperature Sensor
- Engine Misfire
- Fuel Injectors
- Fuel Pump Relay
- Heating Element in Oxygen Sensors
- Idle Air Control Motor
- Idle Speed
- Ignition Coils
- Intake Air Temperature Sensor
- Manifold Absolute Pressure Sensor
- Park/Neutral Switch (Automatic Transmission)
- PCM Internal Self Test
- Radiator Fan Relay
- Throttle Position Sensor
- Vehicle Speed Sensor

The MIL can also display DTC's. Cycle the ignition switch on, off, on, off, on, within 5 seconds and the PCM displays any DTC's stored in memory.

RADIATOR FAN RELAYS - PCM OUTPUT
The PCM energizes the radiator fans through either the low or high speed radiator fan relay The PCM controls the ground circuit for the solenoid side of the relay. Power for both relay solenoids is supplied through a 10 amp fuse in the PDC. Power for both relay contacts is supplied power through a 40 amp fuse in the PDC. Refer to Wiring Diagrams for circuit information.

The PCM monitors the A/C compressor discharge (high side) pressure through the air conditioning pressure transducer. Depending on engine coolant temperature and A/C system high side pressure, both fans operate at either low or high speed.

The radiator fan relays are located in the PDC Fig. 25. The inside top of the PDC cover has a label showing relay and fuse location.

SPEED CONTROL SOLENOIDS - PCM OUTPUT
The speed control vacuum and vent solenoids are operated by the PCM. When the PCM supplies a ground to the vacuum and vent solenoids, the speed control system opens the throttle plate. When the PCM removes the ground from the vacuum and vent solenoids, the throttle blade closes. The PCM balances the two solenoids to maintain the set speed.

TACHOMETER - PCM OUTPUT
The PCM sends engine speed information on the CCD Bus to the Body Control Module for tachometer operation. The PCM calculates engine RPM from the crankshaft position sensor input.